1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a photographing method, and more particularly, to a focusing method of a photographing apparatus including a focus lens and a photoelectric conversion unit, and a photographing apparatus using the focusing method.
2. Description of the Related Art
In the related art, a photographing apparatus includes a focus lens, a photoelectric conversion unit, and a control unit. The photoelectric conversion unit may be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS).
In a focusing method of a photographing apparatus, for example, an automatic focusing method of a security camera, a position at which a maximum focus value is generated is searched for by changing a distance between a focus lens and a photoelectric conversion unit.
For example, in a photographing apparatus including a focus motor, a position at which a maximum focus value is generated is searched for by changing a focus lens in a state where a photoelectric conversion unit is fixed.
By contrast, in a photographing apparatus including a motor of a photoelectric conversion unit, a position at which a maximum focus value is generated is searched for by moving the photoelectric conversion unit in a state where a focus lens is fixed. The photographing apparatus including the motor of the photoelectric conversion unit may be applied to various uses by replacing the focus lens.
When a maximum focus value is searched for and then a focus lens or a photoelectric conversion unit moves to a position of the maximum focus value, a focus value at the position does not correspond to the maximum focus value in many cases. That is, the focus lens and the photoelectric conversion unit may not be accurately placed at an actual position of the maximum focus value.
This seems to be caused by a gear connected to a driving motor of the photoelectric conversion unit or a focus motor.
FIG. 1 is a view illustrating a backlash B in the related art.
Referring to FIG. 1, when teeth of one pair of gears, for example, a pinion 11 and a rack 12, mesh with each other, the backlash BL exists as a clearance between mating surfaces of the teeth.
The backlash BL is a factor designed in consideration of deflection under load or thermal expansion.
However, in a gear connected to a motor of a photoelectric conversion unit or a focus motor, the backlash BL existing between the teeth of the pinion 11 close to the motor and the teeth of the rack 12 close to a lens may cause a focus lens or the photoelectric conversion unit to fail to be accurately placed at an actual position of a maximum focus value.